10. The population of a colony of bacteria doubles every 5 hours. If 1000 bacteria
are present initially, how many bacteria does the colony contain after 2
days?

Solution

At time t=0 hours, the colony contains 1000 bacteria. After t=5 hours, the colony contains 2(1000)=2000 bacteria. After t=10 hours, it doubles again; now the colony numbers 2(2(1000))=22(1000) bacteria. Continuing, we see that in 2 days (or 48 hours), the population of the colony will have doubled times; thus after 2 days, there are bacteria in the colony.